AD/B727/184 - Autopilot Pitch Control Computer (Cth)

AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Boeing 727 Series Aeroplanes

AD/B727/184 Autopilot Pitch Control Computer 8/2003

Applicability: Model 727-100 and 727-200 series aeroplanes, as listed in Boeing Alert Service Bulletin (ASB) 727-22A0093 dated 20 December 2000; excluding aeroplanes equipped with radio altimeter-based autopilots.

Requirement: 1. For any aeroplane on which autopilot coupled ILS approaches with time-based glideslope gain programming are used, revise the Limitations Section, under AUTOPILOT/FLIGHT DIRECTOR SYSTEM, of the Aircraft Flight Manual (AFM) by adding the following (this may be accomplished by inserting a copy of this AD into the AFM):

Coupled ILS approaches are prohibited unless the autopilot has been modified in accordance with AD/B727/184.

CAT II autopilot coupled ILS approach shall not be performed if the Middle Marker (ground or airborne system) is inoperative or nonexistent.

Disconnect the autopilot at, or prior to, 80 ft. (above the runway's touchdown- zone elevation) during coupled ILS CAT II approaches.

2. Unless previously accomplished, modify the existing SP-50 or SP-150 single- channel autopilot in accordance with ASB 727-22A0093.